This is probably because the vast majority of Asian Americans are in fact culturally indistinguishable from anyone else......and quite frankly the possibility that an Asian American might be Buddhist is not something that most Americans really want to know about because it is alien to most Americans who think that Buddhism is a form of idol worship...
Where the heck is this coming from Chownah? I can't even reply to this, the lapse in logic is so profound.
Do you think that in New York walking down the sidewalk or in a department store or through a restaurant that you could successfully indicate which Asian Americans are Christian and which are Buddhist and which are none of the above? Guaranteed you can't for the vast majority.
Do you think that the average American TV viewer gives a whit about Buddhism? Guaranteed they don't.
You also asked:
"In my country we have representation of one particular Dharmic faith throughout or media. We have them depicted in TV serials, soaps, etc as fully formed characters. Is Wendy Wu really the best American media has to offer Asian American Buddhists? Or are they not American enough to warrant representation? Any thoughts?"
My answer is that I guess that Wendy Wu is as good as it gets althought the movie Gran Tourino (overall mediocre bad) had one fairly reasonable representation of an Asian American.
Also, I think you are getting it backwards in that it is not that they are not American enough, it is that they are too American to require representation of their religious beliefs........TV audiences in America are not very interested in watching things to do with religion.....and frankly it seems pretty much the same here in Thailand.
P.S. Don't be too concerned with the lapse in logic.....it can probably be reversed by just cutting down on time viewing TV.